chore: update NuGet packages

[xperiandri]

Proposed Changes

Updated central NuGet package versions in Directory.Packages.props to newer releases across build, compiler, test, and dependency-management tooling. FAKE packages were moved from 6.1.3 to 6.1.4, while FSharp.Compiler.Service, Microsoft.NET.Test.Sdk, MSTest.*, and NuGet.* packages were upgraded to newer major/minor versions. Runtime and library dependencies were also refreshed, including R3 (1.2.9 → 1.3.1) and Unquote (7.0.0 → 7.0.1). build/Changelog.fs was adjusted to preserve changelog.References when constructing the new changelog entry, aligning the release script with the current changelog model signature.

Types of changes

What types of changes does your code introduce to FSharp.Control.R3?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• Build and tests pass locally – not evidenced in diff/commit history
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have added necessary documentation (if appropriate)